To the engineers in the crowd, we’ve open sourced a bit of code that we use heavily in Path and that you might find useful in your own projects.
Fast Image Cache is an Objective-C library that—you guessed it—caches images fast. Use it to cache like-sized images (e.g. profile pictures, photo thumbnails, etc.), persist them to disk, and display them without the overhead of opening files, decoding image formats, or even really copying memory. Images are mapped directly from file to screen. In Path, this allows us to display and scroll lots of images on screen more or less at 60FPS, even on older devices.
For code, documentation, and comparisons, check out the project’s GitHub page: http://github.com/path/FastImageCache
So, why open source? Well, because this library is awesome! Also because, like most small software companies, we rely heavily on the open source community. Giving back to a community we take so much from is the right thing to do. And very simply, as users of iOS software, we hope our little contribution will improve the experiences of other products we love.